What I like about gadgets is that they are really just small HTML pages. That means: No big-project development overhead. If you have Notepad.exe and some knowledge about HTML, then you can write your own gadget. Like HTAs, they run with with full local-program privileges, and can use ActiveX objects. There is no limit to the creative things you can do with gadgets.
How to Create a Gadget (the short version):
Here’s all you need to do to create your own gadget:
1) Write an HTML page, say gadgetName.html
2) Write a short XML file, named (exactly) gadget.xml
3) Copy these